Sound-magnifying phonograph



E. S. PRIDHAM AND P. L. JENSEN.

SOUND MAGNlFYING PHONOGRAPH. APPLICATION HLED JULY 3, 191s.

' 1 ,329, 928. Patented Feb. 3, 1920.

4 SHEETS-SHEEI 1.

g I"! W I WITNESSES: 4 IN VENTORS M 20. 10252 ,dfrz'dam 192 97 Z. Jgnsevz E. PRIDHAM AND P. L. JENSEN.

SOUND MAGNIFYING PHONOGRAPH.

APPLICATION FILED JULY 3, I916.

Patented Feb. 3, 1920.

4 SHEETSSHEET 2- BY WW E. s. PRIDHAM AND P. L. JENSEN.

SOUND MAGNIFYING'PHONOGRAPH.

APPLICATION FILED JULY 3, l9l6.

1,329,928. Patented Feb. 3,1920.

4 SHEETS-SHEET 3.

1 ElT I I 5; I I WITNESSES: INVEN'IIORS 4 23 zmmzmfiM/mm ATTORNEYS E. S. PRIDHAM AND P. L. JENSEN.

souuu MAGNIFYING PHONOGRAPH.

APPLICATION FILED lULY3| I916.

\ Pafented Feb. 3, 1920.

4 SHEETS-SHEEI 4- UNITED STATES PATENT OFFICE.

EDWIN STEWART PRIDHAM AND PETER LAURITS JENSEN, 0F NAPA, CALIFORNIA,

ASSIGNORS TO COMMERCIAL WIRELESS AND DEVELOPMENT 00., OF SAN FRAN- CISCO, CALIFORNIA, A CORPORATION OF ARIZONA.

SOUND-MAGNIFYING PHONOGRAPH.

Specification of Letters Patent.

Patented Feb. 3, 1920.

Application filed July 3, 1916. Serial No. 107,442.

machine or sound magnifying phonograph,

suitable for reproducing sound records in large halls, auditoriums and amphitheaters I and before out-of-door gatherings or whereever manifestly the ordinary talking machine would be inaudible and futile. These results are accomplished through the combination with the ordinary sound box of a talking machine, of a microphone transmitter and a sound amplifier with or without means for varying the volume of sound given out by the amplifier; the sound varying means however, being capable of use with the ordinary talking machine.

One form which our invention may assume is exemplified in the following description and illustrated in the'accompanying drawings in which 9 Figure 1 shows a vertical sectional view of a phonograph embodying our invention.

Fig. 2 shows a plan view of the same.

Fig. 3 shows a fragmentary view of the side of the cabinet illustrating the control means for the electrical connections.

Fig. 4 shows a side elevation of the amplifying receiver employed in our device.

Fig. 5 shows a horizontal sectional View of the device.

Fig. 6 shows a side elevation of the controlling mechanism employed herein.

Fig. 7 shows a diagram of the electrical connections.

Figs. 8 and 9 show plan views of the Fig. 10 shows a vertical longitudinal secthe ordinary phonograph cabinet may be used and our invention applied thereto an attachment. We connect a microphone transmitter 11 to the goose-neck 12 or other conduit communicating -with the ordinary traveling sound box or reproducer 13 of a phonograph; the swinging arm 14, corresponding to the usual sound conducting arm of a phonograph, being out of communication with the goose-neck and sound box. From the microphone, current carrying wires 15 extend to a sound amplifying receiver 16, preferably located within the cabinet of the phonograph.

In general, the sound amplifying receiver comprises a conducting coil 17, for carrying the modulated currents, and which is rigidly attached to a receiver diaphragm 18. This coil is disposed at right angles to the lines of force of a magnetic field created by a magnet 19 energized by coils 20. A current passing through the conducting coil caused by the sound waves will cut transversely the lines of force of the magnetic field with the result that a' reaction takes place which vibrates the coil and actuates the diaphragm. The strength of these vibrations being a product of three factors, viz., length of the conductor exposed to the lines of force, strength of the magnetic field and strength of the current passing through the conductor, by increasing the length of the conductor acted upon by the lines of force and using'a strong magnetic force, a great into. the diaphragm and accurately repros duce the sound waves in greatly augmented volume. In fact, the sounds from an ordinary phonograph equipped with our invention. have been heard at a distance as great as three miles. The musical value of these sounds is in no way impaired by this great amplification, but on the contrary, an improven'ient is noted. Mechanical amplification of.sound destroys the wave lengths and ,is conductive of harshness and blatancy,

whereas, electric amplification preserves the r wave lengths and produces full androunded tones with a consequent rendering of values otherwise lost.

Mounted upon the'receiver in direct com- I munication with-the diaphragm thereof, is

an amplifying horn '21, also within the there is shown a feed circuit comprising mains 23 and 24, the former of which indicates the positive lead and is connected through a suitable resistance coil 25, w th the energizing coils 20 of the magnetic C1I- cuit of the amplifying receiver. From the coils 20, the current passes to a four-pole snap-switch 26, the contacts of which are marked A, B, C and D respectively. The closing and opening of the switch is performed by the rotation of a metallic cross 27. For clearness, we have shown the switch in Figs. 8 and 9 as having one-eighth of a turn, with the contacts all in the same plane, but in practice these switches are given onefourth of a turn and adjacent contacts are in different planes. When the switch is closed, all contacts are in metallic connection with each other, thus providing an arrangement for divided circuits, the purpose of which will be made apparent hereinafter.

The first circuit may be called the energizing and charging circuit and is as follows: Current from the lead 23 flowsthrough the resistance coil 25 to the mag netic coils 20, thence to the contact A of the switch 26 and through the metallic cross arms 27 to the contact D. From contact D a connection leads to the positive pole of the storage battery 22, and the negative pole of the storage battery is connected to the negative lead 24 of the feed circuit. The resistance coil 25, combined with the resistance of the energizing coils 20 should be of such value that the storage battery will receive its normal charging current.

A second circuit controlled by the switch 26 is the transmitter circuit. In this connection we find it desirable to introduce a talking transmitter 28in addition to the phonographic transmitter 11, so arranged that either may be cut in independently, whereby oral announcements, speeches, etc, may be made through the amplifying receiver and the horn between musical renditions. Such an arrangement is exceptionally desirable for publ1c entertainments.

Both transmitters have ,a common wire running to the negative pole of the storage battery and separatewires running to contacts 2,9 and 30 respectively, of a switch 31.

The arm of the switch. 31 is connected is connected to the switch contact B. The

secondary of the coil 33 is connected to the vibrating coil 17 of the amplifyingreceiver. The circuit just described is as follows:

Current from the positive terminal of the a storage battery flows to the contact D, through the switch arm 27 to contact B, thence to the primary of the induction coil 33 and from the primary to the variable resistance 32. From the resistance coil the circuit leads to the arm of the switch 31, where the circuit may be completed either through transmitter 11 or 28, to the negative terminal of the storage battery. The secondary of the induction coil communicates the modulated currents to the movable coil of the ,receiver.

A third circuit controlled by the switch 26 may be termed the indicator circuit and.

comprises a signal lamp 84: connected to the switch point C at one side and to the positive lead 23 at the other side. Current from the contact 0 passes through the signal light to the positive side of the outside circuit. This signal light serves a ver useful purpose in that it indicates that t 1e energizing current is charging the storage battery, and is a visible signal warning the operator to turn the current off when not using the instrument. It is also of use in showing whether the charging current is connected to the properfterminals of the battery, for if the charging current be in series with the battery or the voltage of the battery be added to that of the charging current, the light will glow with increased brightness, while if the terminals are properly connected, the voltage of the charging current less the battery voltage will be the voltage of the lamp circuit and therefore the lamp will glow less brightly.

By introducing more or less resistance into the transmitter circuit and thereby varying the strength of the current passing through the vibrating coil 17 we are enabledto control the volume of sound delivered by the horn, whereby to produce loud, medium, or soft tones, as desired. As shown in Fig. 6, the variable resistance is controlled by a rheostat arm 35 and comprises a series of conducting brackets 36 projecting out from a base-board 37, secured to the interior of the cabinet. These bracketsare arranged in an are about the rheostat arm and each carries a binding post 38 at its opposite ends and has a contact point 39 at its inner end projecting into the path of the rheostat arm. Between the outer end of each bracket and the inner end of the adjacent bracket is a small resistance coil 40, thus putting all of the-brackets and coils in electrical connection with each other. One end of the arc is provided' with a conductor plate 41, to which the end of the adjacent resistance coil is connected and this plate also has a contact for engagement with the rheostat arm and is connected by a wire 42 with the arm of the switch 31. The rheostat arm 35 is connected to the primary of the induction coil 33, and therebyany desired number of resistance coils may be included in the transmitter cir-' uitby manipulating the rheostat arm. The base-board 37 as shown in Figs. 5- and 6 is carried within the cabinet 10 and has 1 dicating devices marked Off and On. A

knob 45 operates the arm of the switch 31 and carries a pointer 46 to register with the indicating devices marked T and M,.

indicating the adjustments for the talking and music transmitters. An aperture 47 is provided inthe switch board and cabinet to permit the signal lamp 34 to be seen. The rheostat arm 35 is operated by a knob 48 which carries ,a pointer 49, the limits of movement of which are marked L an S for loud or soft playing.

An important feature of the switch 26 is the contact B which controls the transmitter circuit. It was discovered in our early work with this switch that upon breakin the con tacts all at the same time, a hig voltage discharge took place around the transmitter circuit, due to the sudden breaking, of the current through the energizing coils of the magnet. As this current was opposedby the storage battery current in the charging direction, but added to it through the transmitter circuit, it will be seen that of the two circuits which could absorb this high voltage, the transmittercircuit took the greater portion of it and this invariably led to the puncturing of the transmitters. To obviate this difliculty the contact point B is made much shorter than the others so that when the metallic arms 27 are rotated to break the contacts, the transmitter circuit will be broken before the others, and in this way all danger of puncturing the transmitters is obviated. p

It will. be noted that by the use of the storage battery, it is possible for us to use the regular 110 volt direct current service with exceptionally good results. The battery is charged with a current slightly in excess of the value used in the transmitter, thus keeping the battery in a fully charged condition at all times. Also the batterv acts as an exceedingly low resistance path for the fluctuating transmitter currents in the transmitter circuit.

4 The variable resistance which is placed in the transmitter circuit is of great valueas a modulator, especially when phonographic music is being reproduced. By means of the rheostat arm, the current may be weakened or strengthened at will, thus easily controlling the volume of the reproduction.

Whilewe have shown and described herein but one form of device, it will be understood nevertheless, that our invention is susceptible ofmodifieation, and therefore'many changes in the construction and arrangement of the several parts may be employed, without departing from the spirit of the invention as disclosed in the appended claims.

Having thus described our invention, what we claim and desire to secure by Letters Patent is* 1. .In an instrument for amplifying sounds, including a transmitter, a receiver,

a signal lamp and a storage battery, circuits for said transmitter, receiver, signal lamp and storage battery, a multi-point switch for controlling said circuits, said switch beingso constructed .as to break said transmitter circuit in advance of said other circuits.

2. In aphonograph, the combination with a record and its reproducer of a microphone transmitter connected with the reproducer, a receiver for said transmitter, said receiver having its field produced by an electromagnet, electrical means in connection with said transmitter and receiver for amplifying sounds, and an electrical circuit, said circuit being adapted to be connected to a commercial direct current supply service, said circuit including a resistance, the energizing coils of the electromagnet of the receiver, and a storage battery in series with said coils and resistance whereby said storage battery receives its proper charging current from the commercial source.

. 3. In a phonograph, the combination with a record and its reproducer, of a transmitter in connection with said reproducer, a receiver for said transmitter, electrical means in connection with said transmitter and receiver for amplifying sounds affecting said transmitter, electric circuits, said circuits comprising a charging circuit connected to a commercial supply source, said charging circuit including the energizing coils of said receiver, a resistance and astorage battery. a transmitter circuit operated by said storage battery, a signal circuit including a lamp, all of said circuits being interconnccted by mcans of a multi-point switch for the control of said circuits, substantially as shown.

4. In a phonograph, the combination with a record and itsreproducer of a microphone means in connection with said receiver for amplifying the sound waves and electrical connections for the transmitter and receiver, said connections including a receiving circuit connected with the service mains, a storage battery in said receiving circuit to receive a charging "current therefrom, a

connections for the transmitter and receiver,-

' said connections including a receiving cir cuit connected with the service mains, a storage battery in said receiving circuit to receive a charging current therefrom, a transmitter circuit operated by said storage battery and a multi-contact switch for con-.

trolling said circuits and putting them all in electrical connection with each other and an indicator circuit connected with said switch and with the positive lead of the service mains.

6. In a phonograph, the combination with a record and its reproducer of a microphone transmitter connected with the reproducer,

a receiver for said transmitter and electromagnetic means 1n connection with said. re-

ceiver for amplifying the sound waves, said means. comprising a conducting coil for the modulated currents secured to the diaphragm of the receiver, an electromagnet for producing lines of force at right angles to the coil, whereby to cause said coil to vibrate the diaphragm, and actuating circuits for said transmitter and-receiver, comprising connections -between the service mains and the amplifying means, a storage,

battery included in said connections to receive a charging current from the service mains and connections between the storage battery and the transmitter for operating the latter, said last named connections ineluding an induction coil having its primary in circuit with the transmitter and its secondary in circuit with the coil on the receiver diaphragm and a variable resistance coil in said transmitter circuit for varying the strength of the current waves whereby to modulate the sounds.

7. In a phonograph, the combination with a cabinet, a record and a reproducing device of a microphone transi'nitter connected with the reproducer, an amplifying receiver carried within the cabinet and connected electrically with the transmitter, an amplifying horn ,on the receiver also contained within the cabinet, a variable resistance device carried wlthin the cablnet and connect. ed with the transmitter circuit for vary ng the strength of the current waves, and means operable from the exterior of the cabinet for controlling said variable resistance device. p

8. i In a phonograph, thecombination with a cabinet, a record and a reproducing device of a microphone transmitter connected with the reproducer, an amplifying receiver carried within. the cabinet and connected electrically with thetransmitter, an ampli fying horn on the receiver also contained within the cabinet, a talking transmitter adapted to be connected with the receiver and means operable from the exterior of the cabinet for cutting the talking. andphonographic transmitters into circuit with the receiver independently.

9. In a phonograph, the combination with a cabinet, a record and a reproducing device of a microphone transmitter connected with the reproducer, an amplifying receiver carried within the cabinet and connected electrically with the transmitter, an amplifying horn on the receiver also contained within the cabinet, actuating means for the transmitter and amplifying receiver, com-Q prising a receiving circuit connected with an outside supply circuit, a storage battery within the cabinet and" connected with the receiving circuit, whereby to receive charging current therefrom, a transmitter circuit connected with the storage battery and actuated thereby and a multi-contact switch forming metallic connections between both circuits and meansoperated from the exterior of the cabinet for controlling said switch, whereby to put the circuits into and out of operation.

10. In a phonograph, the combination with a cabinet, a record and a reproducing device of amicrophone transmitter connected with the reproducer, an amplifying receiver carried within the cabinet and connected electrically withthe transmitter, an

amplifying horn on the receiver also contained within the cabinet, actuating means for the transmitter and amplifying receiver, comprising a receiving circuit connected with an outside supply circuit, a storage battery within the cabinet and connected with the receiving circuit, whereby to receive charging current therefrom, a transmitter circuit connected with the storage battery and actuated thereby and a multicontact switch forming metallic connections between both circuits, means operated from f the exterior of the cabinet for controlling said switch, whereby toput' the circuits into and out of o eration, and a signal light within the cabinet and visible from without, connected with the switch and the supply circuit for indicating the charging of the storage battery and the condition of the circuit connections.

11. In a phonograph the combination of a sound box, a microphone transmitter in eon'nnunication with the sound box, a sound amplifying receiver connected with the transmitter, a horn attached to the amplifier, a rheostat for varying the strength 01 current in the transmitter circuit, to thereby modulate the volume of sound; a storage battery for supplying current to the trans mitter circuit; a dynamo circuit for current to energize the magnetic field oi. the amplifying receiver and recharge the storage battery and switch mechanism to control the circuits by one operation.

12. Ina phonograph, .the combination with a cabinet, a record and a reproducing device, of a transmitter connected with the reproducer, an ai'l'lplifying receiver carried Within the cabinet and connected with the transmitter, an amplifying horn on the receiver also contained within the cabinet, actuating means for the transmitter and amplifying receiver, comprising a storage battery within the cabinet, a transn'litter circuitincluding' the primary of an induction coil connected to said storage battery, a secornlary for said induction coil, said secondary being connected to the actuating coil of said receiver, a signal circuit including a. lamp, said circuits all being contained within thecabinet and one of them being connected-t0 a inulti-point switch, said switch being; )perable from without the cabinet, and a window in the cabinet tl'n'ough which the signal lamp may be viewed.

In testimony whereof we have hereunto set our hands in the presence of two subscribing witnesses.

EDlVIN STEWART PRIDHAM. PETER LAURITS JENSEN.

Witnesses JOHN H. HERRING,

\V. W. HEALEY. 

